When we walk or stand straight for example, we have to keep our position reported to a reference like earth’s ground plane. The same principle is applicable in robotics when robots have to keep its positions reported to a reference. At the base of the measuring position system is the tilt sensor with the role to measure the tilt on two, three or four axes to a reference plane. Two axes measurement is used when the robot is not moving while three and four axes tilt measurement is used when the robot is under moving.

The tilt sensor is used in many fields including games, mobile devices like smartphone or tablet, industrial and service robots. Depending on the robot features, instead using a tilt sensor to measure the tilt angle reported to earth ground plane is used an accelerometer sensor. This could happen only if the robot needs tilt angle information in motion and not in a stationary state. This is one of the differences between these two sensors, an accelerometer sensor cannot measure the tilt when the robot is in a stationary state. Another difference is that a tilt sensor has less functionality compared with an accelerometer sensor, but has a friendly interface than an accelerometer sensor. Using a gyroscope sensor is also a common solution to measure the leaning of the robot. A gyro sensor is designed to measure the angular motion or twist of the robot and is used especially for robotic projects that needs better stability as a human-like robot along with a tilt sensor.

If the robot requirements include a low tolerance on tilt angle, typically is used a tilt sensor instead an accelerometer or gyro solution. Tilt sensors are designed in order to guarantee a high accuracy in monitoring the position. The accuracy of a sensor depends on many factors like vibrations, temperature, gravity, and the list can continue with other typical noises for sensors. A robot can uses wheels or legs for movements and in the same situations, the inclination angle has to be measured for many times in a second if the robot has to maintain a certain position.

The tilt sensor works by using a mercury-switch or a metallic ball that commutes two pins when the sensor is inclined at a certain angle. Any change of sensor angle results in a different value as output.

In robotics, the tilt sensor is used for:

• for self-balancing robot as feedback sensor;
• monitoring the angle of arm and leg;
• sense the change in orientation;

DFRobot Tilt Sensor

Arduino compatible and with a user-friendly interface, the DFrobot tilt sensor is one of the most popular tilt sensor used in robotic applications. The functionality is based on mercury material and the digital output values are based on mercury switches calculation.

Zhichuan Electronics ZCT245AN-TTL

Measuring the tilt on two axes and with accuracy less than 0.5 degrees, ZCT245AN-TTL is one of the most accurate tilt sensors on the market. The tilt range can be measured for up to 60 degrees.

SCA100T Inclinometers

SCA100T has the biggest tilt range for measurement between -90 and +90 degrees on a horizontal plane. The tilt is measured on two axes and the output is digital type.

Tilt Sensor

Designed for Pob technology applied on robots, this sensor has analog output and can measure the tilt between -60 and +60 degrees.

4-Directional Tilt Sensor

Measuring the tilt on four axes, the 4-Directional tilt sensor can be used in robotic applications to measure the tilt while the robot is moving or as an accelerometer sensor. The output is analog type and can be connected easily to a microcontroller. Features include an alarming system that triggers when established parameters are achieved.

RPI-1031 Tilt-a-Whirl Breakout

High precision on four axes are the words that describe the RPI-1031 tilt sensor. It has a flat design and can be integrated easily into a robot.